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Popcorn bark out the intake?

trucksgottaheXJ

NAXJA Forum User
Location
Portsmouth, NH
When I try to troubleshoot my wifes 97' XJ 4.0 auto it usually ends up like a bad episiode on Click and Clack, with her trying to describe the sound the car makes when it's having a problem and me trying to dismiss everthing as an exhaust rattle. Anyhow I have been having an ongoing issue with this XJ where it will run poorly, lose speed, and now recently devloped a low speed stumble. The truck has never stalled (died) it starts everytime and runs well except for uhh....when its not. It's never had to be towed in but I would like to get to the bottem of this. Wife says when it loses power it sounds like our dog when he gets frustrated and "Popcorn Barks" sounds sort of like raw fuel predetonating. The truck is not throwing codes on this and my go to mechanic is at a loss.

So far this year I've put in a coil, crank sensor, and plugs...oddly the rig will run okay for a while after each "fix" but will soon get back to its old ways. I have a source for wholesale parts so I was going to keep throwing sensors till I hit the g spot but it sucks to hack. Any suggestions? What about my MAP sensor, does the 97, have a cam sensor and if so, where?
 
check your plugs, look white/light brown? sounds like fuel starvation
 
Does the problem occur once the jeep is warmed up, or when going uphill/under load?

Fuel pump, O2 sensor, or plugged cat could be the cause of the problem.
 
The problem generally occurs at operating temp. Mechanic checked fuel pressure while driving and saw no drop off. She's been having the issue intermittently since the springtime, I can only assume that if it was the fuel pump it would have failed by now. Could be thou...the truck will sputter, sputter, like its starving for gas and then come back SURGING powerfully back to normal. Rear O2 sensor on this rig had its wiring torn off but I've been told this isn't the source of my troubles.
 
rear o2 sensor is disconnected and its not throwing codes? thats odd.

the o2 sensors help the computer decide how much gas to give the engine, when they fail the engine typically runs rich, causing excessive buildup in the cat, plugging it. that causes excessive backpressure. i would be willing to bet it has alot to do with your problem.
 
GrimmJeeper said:
rear o2 sensor is disconnected and its not throwing codes? thats odd.

the o2 sensors help the computer decide how much gas to give the engine, when they fail the engine typically runs rich, causing excessive buildup in the cat, plugging it. that causes excessive backpressure. i would be willing to bet it has alot to do with your problem.

The rear o2 sensor's job is to make sure the converter is doing it's thing. It doesn't serve any purpose in the air/fuel mixture, that's what the first o2 sensor is for.
 
99XJSPORT06 said:
The rear o2 sensor's job is to make sure the converter is doing it's thing. It doesn't serve any purpose in the air/fuel mixture, that's what the first o2 sensor is for.
i stand corrected. :D
 
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